System of electrical distribution.



No. 645,0l4. Patented Mar. 6, I900.

W. B. 8v. L. C. REED.

SYSTEM OF ELECTRICAL DISTRIBUTION.

(Application filed Oct. 6, 1899.)

(No Model.)

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UNITE STATES PATENT OFFICE.

WARREN B. REED AND LYMAN O. REED, OF NEW ORLEANS, LOUISIANA.

SPECIFICATION forming part of Letters Patent No. 645,014, dated March 6,1900. Application filed October 6, 1899. Serial No. 732,815. (No model.)

T0 (0Z5 whom it may concern.-

Be it known that weflVARREN B. REED and LYMAN G. REED, citizens of theUnited States, residing at New Orleans,in the parish of Orleans andState of Louisiana, have invented new and useful Improvements in Systemsof Multiple-Arc Alternating-Current Transmission and Distribution, ofwhich the following is a specification.

In the present system of high-tension transmission by alternatingcurrents, either single or multiphase, the wires have to be highlyinsulated from each other, from the earth, and from other wires in orderto avoid the losses due to leakage. Alternating systems, however, aresubject to losses other than those due to leakage and ohmic resistance.Inductive resistances, skin effect, and condenser capacity all have tobe taken into account. Without going into the theory of thesephenomena,- it may be stated briefly that in order to partly overcomethe" self-induction of the wire itself several wires have to be usedinstead of one large wire. The skin effect also forbids the use of toolarge a conductor, and from the fact that in overhead construction thewires have to be kept well apart the induction between the wires isincreased by a factor varying with the distance between the wires.IVhere there is more than one circuit on the same pole, there are otherinductive effects between the several circuits, as well as in the wiresthemselves. These effects, due to the alternating flux in the magneticfield surrounding the wires, also induce currents in other circuits,such as telephone-circuits, and frequently interfere with their properoperation. In underground systems these inductive effects areusuallysmall as compared with similar effects in overhead systems, sincethe conductors are placed closer together than they can be in theoverhead system. Still even in underground systems these effects areconsiderable. Since these effects cause the same loss as an increase inthe ohmic resistance, it is of vital importance to eliminate them so faras possible. Besides the inductive losses the wires have a condensercapacity not only between themselves, but between the circuit as a wholeand the earth. In overhead systems this condenser capacity is very smallconrpared with that in the present underground systems; but on anextended system the discharge to earth may be of sufficient capacity tocause a breakdown of the insulation when such discharge takes place overthe interior wiring. here the wires in metallic cables are placedunderground, this condenser capacity is greatly increased and is notonly a continuous strain on the insulation, but is also a consu mer ofcurrent. By our improved system we overcome the objections anddisadvantages above noted by employing metallic-sheathed cables fortransmission and distribution the sheathings of which are utilized asone conductor of the system, are grounded at every available point, andare connected together or bonded to form one common conductor.

The details of the invention will be more fully set forth herein after,and that which we regard as new will be defined in the claims.

In the drawings forming part of this specification, Figure 1 is adiagrammatic View illustrative of the present system ofalternatingcurrent transmission and distribution, and Fig. 2 is asimilar view showing our improved system.

From the generator 1 lead the high-tension mains 2 and 3, supplying thelowtension mains & and 5 through the transformer 6.

Connected with the low-tension mains at and 5 are house-circuits 7 and8, in which the translating devices 9 are interposed. In this system itwill be observed that separate conductors 2 and 3 and at and 5 areemployed for the high-tension and low-tension mains and that twoseparate conductors are employed for the house-circuits, which wires arenecessarily highly insulated from each other.

In Fig. 2, wherein our improvements are illustrated, it will be observedthat the generator 10 has one brush grounded through the wire 11. Fromthe other side of the generator leads the high-tension conductor 12,inclosed in a metallic sheathing or covering 13, from which it isinsulated. tor we may use an ordinary metallic-sheathed cable or anyform of concentric conductor. Thesheathing 13 constitutes one conductorof the high-tension system, and the same is grounded at various points,as shown at 14; It is also connected, and thereby grounded, at

For this conduc the generator through the wire 15, attached to theground-wire 11. The low-tension system is made up of one or moreconductors 16, surrounded by and insulated from a metallic sheath-orcovering 17, the said sheath or covering constituting one of theconductors of the low-tension system and grounded, as shown at 18.Between the high-tension and low-tension systems is a transformer 19,having a metallic sh ell or casing 20, which is electrically connectedthrough the wires 21 22, respectively, with the metallic sheath 13 ofthe high-tension system and with the metallic sheath 17 of thelow-tension system. The primary coil 23 of said transformer is alsocounected to the metallic case 20 and through the wire 24t-with theinterior conductor 12 of the high-tension system. The secondary coil 25of said transformer is also connected to the shell 20 thereof andthrough the wire 26 with the interior conductor 16 of the low-tensionsystem. In this way the grounded metallic casings of the cables of thehigh and low tension systems are bonded together. They are also bondedtogether at other points, as shown at 26. From the low-tension systemleads a house-circuit 27, made up of an inner conductor 28, connected tothe inner conductor 16 of the low-tension mains, and an outer metallicsheathing 29, insulated therefrom, connected to the sheathing 17, andgrounded, as shown at 30. This house-circuit connects with the interiorwiring, in which is located a lamp or other translating device 31, oneend of the filament of said lamp being connected to the interiorconductor 28 and the other end of said filament to the outer sheathing 2A single-pole switch 32 is employed for controlling the insulatedconductor at the entrance of the house.

In our improved system we use for overhead or underground constructionone metallicsheathed cable where the system is two-wire, utilizing themetallic sheathing for one eonductor grounded at every available point.For multiphase systems we employ a plurality of cables, utilizing thebonded and grounded sheathings of all the cables for the conductor ofone phase. The bonding and grounding of all the cable-sheathings ofthese systems at every available point insure the keeping of saidsheathings'or one conductor of the system at the same potential as theearth. Therefore in a single-phase or two-wire system we have oneconductor at a given potential from the earth and the other conductor atthe same potential as the earth and joined in parallel with the earth atevery point of grounding. The translating devices are therefore inmultiple are between the insulated conductor and the earth, and anyleakage or breakdown is of the same nature as the current flowingthrough translating devices and cannot in any way affect the potentialof the grounded outerconductor. Besides, we avoid all induction due tothe circuits and the consequent loss due to this cause. Ne also avoidall interference with other circuits and secure protection to theinterior conductors and to othercircuitsfromcrosses. Moreover, weobtaina great saving in construction, due to the fact that one large conductormaybe used for a circuit instead of many small wires, which are nownecessary to eliminate induction; a saving in the skin effect, due tothe use of large conductors, in the present system; the elimination ofall insulation except between the metallic sheathing and its interiorconductor; the protection of this insulation from the deterioratinginfluences of the weather by the use of the outer casing; theelimination in overhead construction of all cross-arms, pins, andhigh-grade insulators, and the great advantage of being able to placeall of the cables, not only of the system under consideration, but alsoof every system, high or low tension, together and bond and ground themby means of the same pole. This does not increase the difference ofpotential between any interior conductor and its outer casing; but itabsolutely insures that each interior conductor of any system remain atthe difference of potential with its casing which is impressed at thesource of supply. Furthermore, the use of the m etallic-sheathed cables,with the outer casing grounded and constituting one conductor, reducesthe condenser capacity to a minimum, effects a diminution ofcondenser-current, and lessens the strain on the insulation.

The protection of the high-potential conductors according to ourimproved system by a grounded sheath has the further advantage ofavoiding the danger to life now existent in high-tension systems.Breakdowns in transformers are also made less likely, and should oneoccur it could do no damage to the interior wiring, since it would causethe melting of the primary fuses controlling the transformer. Thelow-tension distribution is protected by a metallic sheathing whichconstitutes one conductor, as in the high-tension system, and isconnected to the sheathing of the high-tension cable at the transformerand at other points. The low tension system maybe two or three wire,single or multiphase, as desired; but in any case the exterior easing ofthe cable or cables forms one conductor. House-services are taken offthis low-tension system and are of any number of wires, according to thesystem used. The interior wiring is a system of concentric wiring withone separate conductor eliminated, and the cable-sheathing or a metallicconduit is used for said conductor, the same being connected to theoutside grounded sheathing and otherwise grounded at every availablepoint. In other words, in our improved system of alternating-currenttransmission and distribution, whether single or multiphase, we groundone conductor formed by a metallic cablesheating, which entirelysurrounds the insulated interior conductor or conductors, and carry thisgrounded proteetingsheathing and conductor from the high-tension dynamoto the translating device in the house-wiring.

In the foregoing description we have referred to the distribution oflow-tension alternating current obtained by means of transformers. It isobvious, however, that our invention is adapted for use in connectionwith rotary converters employed for the purpose of securing alow-tension direct current.

Having thus described our invention, what we claim as new, and desire tosecure byLetters Patent, is-

1. A high-tension system of transmission and distribution of alternatingelectric current in which one wire or cable as a separate conductor iseliminated, comprising one or more conductors in metallic coveringswhich are insulated therefrom, and anotherconductor formed by saidcoverings, in combination with atransformer, and a low-tension systemleading therefrom comprising one or more conductors in metalliccoverings which are insulated therefrom, and another conductor formed bysaid coverings, the coverings of the conductors of the high and lowtension systems being bonded independently of said transformer, as andfor the purpose set forth.

2. A high-tension system of transmission and distribution of alternatingelectric current in which one wire or cable as a separate conductor iseliminated, comprising one or more conductors in metallic coveringswhich are insulated therefrom, and anotherconductor formed by saidcoverings, in combination with a transformer, and a low-tension systemleading therefrom, comprising one or more conductors in metalliccoverings which are insulated therefrom, and another conductor formed bysaid coverings, the coverings of the conductors of the high and lowtension systems being bonded independently of said transformer andgrounded, as and for the purpose set forth.

3. A high-tension system of transmission and distribution of alternatingelectric current, in which one wire or cable as a separate conductor iseliminated, comprising one or more conductors in metallic-sheathedcables, and another conductor formed by the sheathings ofsaid cables, incombination with a transformer, and a low-tension system leadingtherefrom comprising one or more conductors in metallic-sheathed cables,and another conductor formed by the sheathings of said cables, thesheathings'of the cables of the high and low tension systems beingbonded independently of said transformer and grounded, as and for thepurpose set forth.

4. The combination of a high-tension and a low-tension system ofdistribution of alternating electric current,each comprising one or moreconductors in metallic-sheathed cables and another conductor formed bythe gronnded sheathings of said cables, a transformer, the primary coilof which is connected with the inner conductor of the high-tensionsystem, the secondary coil of which is connected with the innerconductor of the low-tension system, and both coils of which areconnected with the grounded metallic sheathings of the cables of both ofsaid systems, and a bond, independent of said transformer, between thesheathings of the conductors of the high and low tension systems.

.5. The combination of a high-tension and a low-tension system ofdistribution of alternating electric current,each comprising one or moreconductors in. metallic-sheathed cables and another conductor formed bythe grounded sheathings of said cables, a transformer consisting of ametallic shell or casing electrically connected to the sheathings of thecables of both the high and low tension systems, the primary coil'ofsaid transformer being connected to said shell and to the interiorconductor of the high-tension system, and the secondary coil of saidtransformer being connected to said shell and to the interior conductorof the low-tension system, and a bond, independent of said tranformer,between the sheathings of the conductors of the high and low tensionsystems, as and for the purpose set forth.

6. The combination of a high-tension and a low-tension system ofdistribution of alternatin g electric current, in which one Wire as aseparate conductor is eliminated, each comprising one or more conductorsin metallicsheathed cables and another conductor common to both systems,formed by the bonded and grounded sheathings of the cables of bothsystems, a transformer between the high and low tension systems, ahouse-circuit leading from the low-tension system and translatingdevices therein, the said house-circuit comprising one or moreconductors in metallicsheathed cables, and another conductor formed bythe sheathings of said cables, the said sheathings being grounded, andleading from the translating devices to the sheathings of theconductor-cables of the low-tension system, and the bonds between thesheathings of the cables of the high and low tension sys- IIO tems beingindependent of said transformer,

\VARREN B. REED. LYMAN C. REED.

Witnesses:

ALoNzo' CHURCH, HARRY H. WATERS.

